Self-opening sludge centrifuge



Feb. 26, 1963 H. w. THYLEFORS SELF-OPENING SLUDGE CENTRIFUGE Filed May 11, 1959 RM mwv my.

M 1, W. m mw ya f 3,079,069 SEL @PENING SLUDGE CENTRIEUGE Henrie Wilhelm Thyiefors, Stockholm, Sweden, assignor to Akiieholaget Separator, Stockholm, Sweden, a corporation of Sweden Filed May 11, 1959, See. No. 812,272 (Ilaians priority, application Sweden May 16, 1958 1 Claim. (Cl. 233-420) The present invention relates to centrifugal separators f the type having a controllable sludge discharge system, and more particularly to such separators in which the rotating bowl has a slide-valve movable axially of the bowl so as to alternately cover and uncover sludge discharge openings in the peripheral portion of the bowl.

Centrifuges of this type are well known in the art, as shown, for example, in Bjornstjerna Patent No. 2,178,547, dated November 7, 1939.

In centrifuges of this type, it is customary to organize the parts so that an annular sealing flange of the controllable slide-valve member disengages an 'O-ring seal to permit discharge of sludge through the bowl periphery. Under that arrangement, repeated discharge of sludge particles causes erosion of the '0-ring seal as well as of the sealing flange of the slide-valve. Erosion of the ring seal is no major problem, since it is readily replaceable; but erosion of the slide-valve flange is a serious problem due to the necessity of re-facin-g it from time to time, which is expensive and involves lost of productivity of the centrifuge while the re-facing is being effected.

It has been attempted to overcome this objection by installing on the flange of the slide-valve a packing ring which can be replaced as necessary without disassembiing the machine. With this arrangement, however, sludge is occasionally forced into the space between the slide-valve flange and its replaceable packing ring, causing an imperfect sealing when the sludge discharge is supposed to be cut off. Also, continued operation of this type of sealing arrangement causes erosion of the heads of the screws securing the packing ring to the slide-valve, thus making replacement difficult if not impossible.

The principal object of my invention is to provide a centrifuge of the type described which overcomes the above-noted difliculties.

According to the invention, the slide-valveis provided within the bowl with a detachable liner which serves as protection against erosion; and this liner, in turn, is provided with a generally radially directed outer sealing flange covering what would otherwise be the sealing surface of the slide-valve flange. The liner is preferably secured to the slide-valve by releasable means located radially inward from the outer sealing flange of the liner, that is, at an inner region where the effect of erosion from sludge is substantially reduced or non-existent. With this arrangement, those surfaces of the slide-valve which are most subject to erosion (the surface near the bowl periphery) are protected by the liner against erosion. Also, by extending the liner to the central portion of the slide-valve (at the region of the bowl axis), as in the preferred construction, not only is the slidevalve entirely protected from erosion but it is impossible for sludge to become lodged between the slide-valve and its liner. The liner can be readily replaced without any considerable interruption of the centrifuge operation, and the replacement cost is a small fraction of the cost of re-facing the slide-valve or replacing it.

For a better understanding of the invention, reference may be had to the accompanying drawing, in which the single illustration is a vertical sectional view of part of a centrifuge bowl embodying a preferred form of my invention.

3,?,@ Patented Feb. 25, 1963 In the drawing, the centrifugal bowl 1 is adapted for rotation about its central vertical axis A. The bowl cover 2 is locked to the bowl by means of a locking ring 3. A set of conical discs, indicated at 4, rests on a distributor 5 forming a central feed passage 5:2. for the material to be separated. On its lower surface, the distributor 5 carries radial impeller vanes 6 for imparting. rotation to the feed material entering the separating chamber in which the discs 4 are located.

A slide-valve '7 is mounted in the bowl 1 for sliding movements axially of the bowl, the slide-valve surrounding the central nave 1a of the bowl. The axial sliding movements of the valve 7 may be effected hydraulically by any of the arrangements disclosed in said Bjornstjerna Patent No. 2,178,547. As shown, the bowl spindle 15 has an axial passage 16 for feeding hydraulic liquid to the space 17 between valve 7 and the bottom of bowl 1, and the space 17 has peripheral outlets 18 which discharge the hydraulic fluid at a lower rate than it is fed through passage 16. Thus, when the space 17 is completely filled with hydraulic fluid, the valve 7 is held in its raised position as illustrated, but when the feed through passage 16 is interrupted, the liquid drains from space 17 through outlets 18, whereby the liquid pressure in the separating chamber of the bowl forces valve 7 to its lower position. Upon resumption of the feed through passage 16, hydraulic liquid again accumulates in space 17 and lifts valve 7 to its raised position.

At its outer portion, valve 7 has an annular, radiallyex-tending, sealing flange 8 which, by coaction with a sealing ring 9 secured in the bowl cover 2, serves to open and close sludge discharge openings 10 spaced along the peripheral wall of bowl 1.

The upper surface of slide-valve 7 is covered by a liner 11 of erosion-resistant material, such as sheet metal or plastic reinforced with fiber-glass. At its outer edge, the liner 11 has a radially-directed flange 12 covering the flange or sealing surface 8 of the slide-valve 7. The liner 11 has a shape conforming to the annular concave shape of the upper surface of slide-valve 7. The circular inner edge of liner 1]; is provided with a flange 13 extending radially inward and seated on a step of valve 7, to which it is secured by relasable means in the form of a clamping ring or nut 14 screwed on the central up per portion of valve 7.

It will be understood that when the slide-valve 7 is in its raised position, the outer flange 12 of the liner is pressed against the sealing ring 9 to effect tight closure of sludge outlets 11 Upon downward movement of valve 7 to open these outlets, the liner flange 12 eflectively protects the sealing flange 8 of the slide-valve from erosion by the sludge discharging through outlets do. The central clamping nut 14 permits ready replacement of the liner 11 and is located at a region where erosive action by the sludge is at a minimum.

I claim:

In a rotatable centrifugal bowl of the type having a separating chamber provided at its outer periphery with an outlet for discharge of separated sludge, the outer portion of said chamber forming an annular sludge accumulating zone, the combination of a slide-valve movable in the bowl axially thereof in opposite directions and having a surface extending inwardly from said periphery toward the rotation axis of the bowl, the slide-valve also having an outer flange adjacent said outlet and forming a sealing surface operable to open and close said outlet upon sliding of the valve in opposite directions, a central distributor in the bowl for distributing feed material to said chamber and having a hollow lower portion overlying said inwardly extending surface of the valve, a

detachable liner on the slide-valve partially defining the tributor and defining with said distributor a feed passag and releasable means carried by the valve and engaging said inner portion of the liner for securing the liner to said valve surface.

References (Iite'rl in the file of this patent UNITED STATES PATENTS 631,680 Staahlgren Aug. 22, 1-899 4 Gish Feb. 20, 1934 Nyrop Aug. 31, 1937 Bjornstjerna Nov. 7, 1939 Ortenblad Nov. 8, 1949 Harris Jan. 29, 1957 Krebs Q. Apr. 2, 1957 Steinacker Dec. 12, 1961 FOREIGN PATENTS Great Britain Apr. 2, 1948 Germany Nov. 18, 1935 France Aug. 23, 1950 

